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    <title>Document</title>
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    <script>
        /* 
        Math.max()
        Math.min()
        Math.ceil()    向上取整
        Math.floor()   向下取整
        Math.round()   四舍五入
        Math.random()  随机数
        */

        var num = 12.66;
        console.log(Math.ceil(num))  // 13
        console.log(Math.floor(num)); // 12
        console.log(Math.round(num)); // 13
        console.log(Math.random());

        /*  1-100
        Math.random()*100
        0<=num<99.99
        Math.floor(Math.random()*100)
        0<=num<99
        Math.floor(Math.random()*100)+1
        1<=num<100
        */
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